Hydraulically operable hand tools



April l1, 1961 A. ENGQulsT ETAL HYDRAULICALLY OPERABLE HAND TooLs 4 Sheets-Sheet 1 Filed April 30. 1959 hrentw-s Arne LUIS/ 529esaarS-anell.

Aprxl 1l, 1961 A. ENGQulsT ETAL 2,979,032

HYDRAULICALLY OPERABLE HAND TOOLS Filed April 30, 1959 4 Sheets-Sheet 2 April 11, 1961 A. ENGQulsr Erm. 2,979,032

HYDRAULICALLY OPERABLE HAND TooLs Filed April 30, 1959 4 Sheets-Sheet 3 Figi.

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/4 muesli April 11, 1961 A. ENGQuls'r ErAL 2,979,032

HYDRAULICALLY OPERABLE HAND TooLs Filed Apri 30, 1959 -4 Sheets-Sheet 4 .Illmlllllll @3% MJVVM United States Patent HYDRAULICALLY OPERABLE HAND TOOLS Arne Engqnist, Enkoping, and Eber Oscar Svanell, Skultorp, Sweden, assignors to Aktiebolaget Bahco, VStockholrn, Sweden, a corporation of Sweden Filed Apr. 30, 1959, Ser. No. 810,075

Claims priority, application Sweden May 12, 1958 3 Claims. (Cl. 121-3) The present invention relates to an improvement and development of hydraulically operable hand tools of the type in which two working members, e.g. a pair of shears, a pair of compressing or lifting jaws or a die and a stamp, etc., are to be moved simultaneously toward and away from each other to carry out a working operation, under the action of a pair of pistons which are displaceable in a cylinder in the tool head and adapted to be hydraulically actuated by the aid of a manual pump. A hydraulically operable hand tool of this type is described and shown in the Swedish Patent No. 159,826.

The main object of the present invention is to make such a tool more versatile so that the working members, i.e. the shears, the jaws, dies, etc. can be exchanged while the tool handle with pump, cylinder, and pistons is retained.

This and other objects which will become apparent as the description proceeds are achieved by making the piston cylinder with such a length that, when the working members are in a position close together, the portions of the working members cooperating with the pistons can be freely removed over the rims of the cylinder ends after relieving the pressure on the pistons so that the pistons are no longer in engagement with the working members.

Another aspect of the invention relates to means for ensuring equal movements of the two working members toward or away from each other. It was found that such equal movements are not always achieved in hitherto known tools of the type herein referred to, because the movement of each working member will depend on the movement of the piston associated therewith. If one piston operates with a greater friction in the cylinder than the other, this will result in the latter piston being displaced more than the first-mentioned piston under the action of the hydraulic pressure and hence in one Working member being displaced more than the other, which may lead to an unsatisfactory or even defective Working result.

The invention will be described more in detail below with reference to the accompanying drawings, which illustrate some embodiments thereof.

Figure l shows a hydraulically operable hand tool in longitudinal section, the working members being shown as a pair of shears.

Figures 2 and 3 show the tool in two different elevations.

Figure 4 shows the shears being detached from the remainder of the tool.

Figure 5 shows an auxiliary member useful for faciltating removal of the shears.

Figure 6 shows how the shears may be provided with auxiliary working members to apply pressure, e.g. to drive out a hinge bolt.

Figure 7 is a view of Figure 6 seen from below.

Referring to Figure l, the numeral 1 designates a tool shaft which has an inner cavity 2 for accommodating the liquid which is to serve as the hydraulic uid. The

2,979,032 `Patterned .Apr 11, 1961 cavity 2 is filled with hydraulic uid, before the hand tool is used, and thus constitutes the source of hydraulic uid. A pump piston 3 operates in a cylinder 4 and is adapted to be actuated Iby means of a pump lever 6 which is pivotally mounted on the shaft 1l by means of a link 5. The pump lever 6 is connected to the piston 3 through a link rod 7 and a valve housing 8 which is screwed onto the piston 3, said Valve housing accommodating together with the piston a spring-biased intake valve 9. Adjacent the front end of the cylinder 4 is the pressure valve 10 through which pressure fluid is forced during the working stroke of the pump piston to enter a cylinder 12 formed in the tool head 11. Two pistons 13, 14 are displaceable in the cylinder 12. At their remote ends, the pistons 13, 14 have hemispherical engaging lugs 15, 16which are adapted to act on the Working members mounted in the tool in each particular case. in the embodiment illustrated in Figure l these working members consist of a pair of shears 17, 18 which are pivotally connected together by means of a pair of plates 19, 20 and bolts 21, 2'2 and are acted upon by a helical spring 23 which tends to move the blades of the shears 17, 18 away from each other, but is prevented therefrom when the blades are kept forced toward each other by the action of the hydraulic pistons 13, 14 which with their lugs 15, 16 engagefpans 52, 53, which may be adjustable, in the rear ends of the shears. To relieve the hydraulic pressurein the cylinder 12 a valve 25 in the return passage 26 is used, which valve is opened and closed by means of a screw 24. The screwv 24 is only opened in order to relieve the hydraulic pressure in the cylinder 12.

As seen most clearly in Figure 4, the Working members used, in the embodiment illustrated, the shears 17, 18 with plates 19, 20, bolts 21, 22, and screw 23, may be removed in a very simple manner from the remainder of the tool, eg. to exchange the shears against jaws or punches orthe like.

To remove the Working member assembly 17-23 it is only necessary to bring the blades of the shears 17, 18 close together and to lock them in this position, e.g. by means of a locking member 29 whichis inserted into holes 27, 28 provided for this purpose in the shear blades, whereupon the pans 52, 53 may belifted olic from the hemispherical engaging lugs 15, 16 of the pistons 13, 14 after the pistons 13, 14 have been permitted to yield and move slightly toward each other by opening the return passage 26. It will be understood that when the shears 17, 18, are locked by means of thel locking member 29, the helical spring 23 is rendered inactive, so that there is no automatically acting force to return the pistons 13, 14 toward each other when the return passage 26 is opened, which on the other hand is the case when the shears 17, 18 are not locked together by the locking member 29 after being brought together. The numerals 30, 31 and 32 designate elastic sleeves which serve only to prevent dirt and dust from entering into the tool mechanism. The numeral 33 designates a plunger acted upon by a helical spring 34 and serving to ensure a steady delivery of fluid from the cavity 2 to the cylinder 4 when the piston 3 makes its suction stroke.

To achieve a fully equal angular movement between the shears as they are moved toward eachl other under the action of the hydraulically actuated pistons 13, 14, the shears may be provided with recesses 35 and a roll 36 positioned between them, the roll 36 preferably being of a diameter slightly smaller than the width of the recesses 35, so that the roll 36 will bear on the recesses 35 at the points a, b, c, d.

lf, when the shears are brought together, one of the shears, e.g. the shear 17, for some reason moves somewhat faster from the other shear, 18, the shear 17 will bear on the roll 36 at the point a, which results in the roll transmitting the pressure to the point d, thereby forcing the shear 18 to swing a little more rapidly. The eiiect will, 'of course, be similar if vthe shear 17 lags slightly behind. The pressure of the shear 18 will then be transmitted from the point c to the point b by the intermediary of the roll 36.

Figures 6 and 7 illustrate how the tool, without exchange of Working members, may be provided with auxiliary working mernbers so that the tool can be used for punching or, as contemplated in the embodiment illustrated in Figures 6 and 7, to drive out a hinge pin, a work which is very diiiicult, particularly in the case of automobile doors which are to be repaired or exchanged, because the pin cannot be knocked out with the aid of a mandrel, as the material in the pin will then be upset.

As seen in Figure l, the shears are provided not only with the holes 27, `28 but also with the holes 37, 38 whereby it is possible by means of bolts 39, 40 and 41, 42 to secure the two auxiliary working members 43 and 44. As illustrated working member 43 is forked at its outward end 45 forming bearing surfaces 46 adapted to bear on the upper edge of the hinge,vthe fork opening being sufliciently large to allow substantially free passage of the head of the hinge pin 47.

The working member 44 on lthe other hand is provided with a fork 48 from which projects a mandrel 50 attached to a rotatably mounted transverse bolt 49. The mandrel 50 is intended, when the auxiliary working members 43, 44 are forced toward each other by the action of the pistons 13, 14, to engage the lower end of the hinge pin 47 with a progressively increasing pressure which serves to push out the hinge pin without upsetting the lower end thereof.

Y It will be readily understood that the auxiliary work-k ing members 43, 44 may be formed so as to replace completely the cutting shears, exchange in that case taking place as shown in Figure 4.

It will be apparent from the drawings that the shears as Well as the compressing or punching members may be swung to a position at any desired angle from the axis of the tool shaft 1 around the axis of the cylinder 1Q.. In order to achieve some degree of xation of the swingable portion in the desired angular position, the helical spring 23 referred to above may be arranged so, that its middle portion engages frictionally the middle portion 51 of the cylinder.

We claim:

l. In a hydraulically'operated hand tool comprising a tool headhaving a cylinder provided axially therein, and having a pair of pistons displaceable in the cylinder and manual pump means connected to the tool head for displacing the pistons;V the improvement which comprises working members pivoted together for complemental movement about an axis transverse to the cylinder, said cylinder having opposing open outer ends, said members having complemental outer ends and inner ends itting over the outer ends of the cylinder and engaged by the pistons and the length of the cylinder being such that, when the members are brought close together with their other ends locked together, the inner ends thereof may be freely removed over the outer ends of the cylinder after relieving the pressure on the pistons so that the pistons are no longer in engagement with the inner ends of the members.

2. A hydraulically operated hand tool, as claimed in claim l, wherein a separate locking member is provided for locking the members in a locked position.

3. A hydraulically operated hand' tool, as claimed in claim 1, wherein said pistons have coaxially reduced outer ends and said inner ends of the members and outer ends of the pistons are formed with complemental ball and socketsurfaces.

4. A tool as defined in claim 1 in which the working members are acted upon by a spring which tends to re turn the working members and hence the pistons to an inoperative position as soon as the hydraulic pressure acting on the pistons is relieved.

5. A tool as defined in claim 4 in which the spring consists of a tension spring which is disposed between the working members and which, if the Working members are swingable around the axis of the pistons, also serves as a frictional restraining member acting against the tool head. v

6. A tool as defined in claim 1 in which the working members are provided with attachment means for attaching auxiliary working members.

7. A tool as defined in claim l which comprises means disposed between the two working members to cause the working members to carry out equal movements even if the pistons move at dilerent speeds due to different frictional resistance.

8. A tool as dened in claim 7 in which said means comprises a body positioned between the Working members and adapted to transmit pressure from one working member to the other.

References Cited in the le of this patent UNTTED STATES PATENTS FOREIGN PATENTS Sweden July 23, 1957 

